Neural implant technology is being developed to address many types of neural illnesses including deafness, blindness, impaired motor control, etc., and can have a profound effect in increasing the abilities of persons affected by such neural illnesses. In the development of neural prostheses, there is a need to increase the number of electrodes which are used for neural stimulation beyond that which are presently available. This is especially the case for retinal prostheses (also termed visual prostheses) where simulations have indicated that up to one thousand neural stimulation electrodes will be required to provide the ability to read and to recognize faces.
The present invention addresses this need for an increased number of neural stimulation electrodes by providing a demultiplexer circuit which can be used in conjunction with a conventional neural prosthesis (also termed a neural stimulator) to increase the number of electrodes that can be actuated by a factor of 2N with N being an integer which is generally in the range of 2-4. This can be used, for example, to scale up a conventional 60-electrode retinal prosthesis, which is currently being used for clinical trials, by a factor of 22=4, 23=8 or 24=16 thereby allowing this 60-electrode retinal prosthesis to be used to actuate 240, 480 or 960 electrodes.
The demultiplexer circuit of the present invention has its own dc power supply formed on the same semiconductor substrate so that no external dc voltages are needed to operate the demultiplexer circuit thereby avoiding any possibility for electrolysis.
The demultiplexer circuit of the present invention also provides electrostatic discharge protection to prevent damage of the demultiplexer circuit during implantation of the neural prosthesis or thereafter.
These and other advantages of the present invention will become evident to those skilled in the art.